diff --git a/include/xo/interpreter2/define/IGCObject_DVsmDefContFrame.hpp b/include/xo/interpreter2/define/IGCObject_DVsmDefContFrame.hpp
index 4cb21afa..131d57ae 100644
--- a/include/xo/interpreter2/define/IGCObject_DVsmDefContFrame.hpp
+++ b/include/xo/interpreter2/define/IGCObject_DVsmDefContFrame.hpp
@@ -57,7 +57,7 @@ namespace xo {
             /** move instance using allocator **/
             static Opaque shallow_move(DVsmDefContFrame & self, obj<ACollector> gc) noexcept;
             /** during GC: forward immdiate children **/
-            static size_type forward_children(DVsmDefContFrame & self, obj<ACollector> gc) noexcept;
+            static void forward_children(DVsmDefContFrame & self, obj<ACollector> gc) noexcept;
             ///@}
         };
 
diff --git a/include/xo/interpreter2/detail/IGCObject_DClosure.hpp b/include/xo/interpreter2/detail/IGCObject_DClosure.hpp
index 86becbdf..c0d7d22b 100644
--- a/include/xo/interpreter2/detail/IGCObject_DClosure.hpp
+++ b/include/xo/interpreter2/detail/IGCObject_DClosure.hpp
@@ -57,7 +57,7 @@ namespace xo {
             /** move instance using allocator **/
             static Opaque shallow_move(DClosure & self, obj<ACollector> gc) noexcept;
             /** during GC: forward immdiate children **/
-            static size_type forward_children(DClosure & self, obj<ACollector> gc) noexcept;
+            static void forward_children(DClosure & self, obj<ACollector> gc) noexcept;
             ///@}
         };
 
diff --git a/include/xo/interpreter2/detail/IGCObject_DVsmApplyClosureFrame.hpp b/include/xo/interpreter2/detail/IGCObject_DVsmApplyClosureFrame.hpp
index 01bef341..2a2e9034 100644
--- a/include/xo/interpreter2/detail/IGCObject_DVsmApplyClosureFrame.hpp
+++ b/include/xo/interpreter2/detail/IGCObject_DVsmApplyClosureFrame.hpp
@@ -57,7 +57,7 @@ namespace xo {
             /** move instance using allocator **/
             static Opaque shallow_move(DVsmApplyClosureFrame & self, obj<ACollector> gc) noexcept;
             /** during GC: forward immdiate children **/
-            static size_type forward_children(DVsmApplyClosureFrame & self, obj<ACollector> gc) noexcept;
+            static void forward_children(DVsmApplyClosureFrame & self, obj<ACollector> gc) noexcept;
             ///@}
         };
 
diff --git a/include/xo/interpreter2/detail/IGCObject_DVsmApplyFrame.hpp b/include/xo/interpreter2/detail/IGCObject_DVsmApplyFrame.hpp
index a3e0d31b..83d88686 100644
--- a/include/xo/interpreter2/detail/IGCObject_DVsmApplyFrame.hpp
+++ b/include/xo/interpreter2/detail/IGCObject_DVsmApplyFrame.hpp
@@ -57,7 +57,7 @@ namespace xo {
             /** move instance using allocator **/
             static Opaque shallow_move(DVsmApplyFrame & self, obj<ACollector> gc) noexcept;
             /** during GC: forward immdiate children **/
-            static size_type forward_children(DVsmApplyFrame & self, obj<ACollector> gc) noexcept;
+            static void forward_children(DVsmApplyFrame & self, obj<ACollector> gc) noexcept;
             ///@}
         };
 
diff --git a/include/xo/interpreter2/detail/IGCObject_DVsmEvalArgsFrame.hpp b/include/xo/interpreter2/detail/IGCObject_DVsmEvalArgsFrame.hpp
index 42c26b03..cd53aa9d 100644
--- a/include/xo/interpreter2/detail/IGCObject_DVsmEvalArgsFrame.hpp
+++ b/include/xo/interpreter2/detail/IGCObject_DVsmEvalArgsFrame.hpp
@@ -57,7 +57,7 @@ namespace xo {
             /** move instance using allocator **/
             static Opaque shallow_move(DVsmEvalArgsFrame & self, obj<ACollector> gc) noexcept;
             /** during GC: forward immdiate children **/
-            static size_type forward_children(DVsmEvalArgsFrame & self, obj<ACollector> gc) noexcept;
+            static void forward_children(DVsmEvalArgsFrame & self, obj<ACollector> gc) noexcept;
             ///@}
         };
 
diff --git a/include/xo/interpreter2/env/IGCObject_DLocalEnv.hpp b/include/xo/interpreter2/env/IGCObject_DLocalEnv.hpp
index 55064b27..8576aeda 100644
--- a/include/xo/interpreter2/env/IGCObject_DLocalEnv.hpp
+++ b/include/xo/interpreter2/env/IGCObject_DLocalEnv.hpp
@@ -57,7 +57,7 @@ namespace xo {
             /** move instance using allocator **/
             static Opaque shallow_move(DLocalEnv & self, obj<ACollector> gc) noexcept;
             /** during GC: forward immdiate children **/
-            static size_type forward_children(DLocalEnv & self, obj<ACollector> gc) noexcept;
+            static void forward_children(DLocalEnv & self, obj<ACollector> gc) noexcept;
             ///@}
         };
 
diff --git a/include/xo/interpreter2/ifelse/IGCObject_DVsmIfElseContFrame.hpp b/include/xo/interpreter2/ifelse/IGCObject_DVsmIfElseContFrame.hpp
index ab9a13c8..18297357 100644
--- a/include/xo/interpreter2/ifelse/IGCObject_DVsmIfElseContFrame.hpp
+++ b/include/xo/interpreter2/ifelse/IGCObject_DVsmIfElseContFrame.hpp
@@ -57,7 +57,7 @@ namespace xo {
             /** move instance using allocator **/
             static Opaque shallow_move(DVsmIfElseContFrame & self, obj<ACollector> gc) noexcept;
             /** during GC: forward immdiate children **/
-            static size_type forward_children(DVsmIfElseContFrame & self, obj<ACollector> gc) noexcept;
+            static void forward_children(DVsmIfElseContFrame & self, obj<ACollector> gc) noexcept;
             ///@}
         };
 
diff --git a/include/xo/interpreter2/sequence/IGCObject_DVsmSeqContFrame.hpp b/include/xo/interpreter2/sequence/IGCObject_DVsmSeqContFrame.hpp
index d654d8a1..ca457e3d 100644
--- a/include/xo/interpreter2/sequence/IGCObject_DVsmSeqContFrame.hpp
+++ b/include/xo/interpreter2/sequence/IGCObject_DVsmSeqContFrame.hpp
@@ -57,7 +57,7 @@ namespace xo {
             /** move instance using allocator **/
             static Opaque shallow_move(DVsmSeqContFrame & self, obj<ACollector> gc) noexcept;
             /** during GC: forward immdiate children **/
-            static size_type forward_children(DVsmSeqContFrame & self, obj<ACollector> gc) noexcept;
+            static void forward_children(DVsmSeqContFrame & self, obj<ACollector> gc) noexcept;
             ///@}
         };
 
diff --git a/include/xo/interpreter2/vsm/IGCObject_DVirtualSchematikaMachine.hpp b/include/xo/interpreter2/vsm/IGCObject_DVirtualSchematikaMachine.hpp
index 71786a28..0a51165e 100644
--- a/include/xo/interpreter2/vsm/IGCObject_DVirtualSchematikaMachine.hpp
+++ b/include/xo/interpreter2/vsm/IGCObject_DVirtualSchematikaMachine.hpp
@@ -57,7 +57,7 @@ namespace xo {
             /** move instance using allocator **/
             static Opaque shallow_move(DVirtualSchematikaMachine & self, obj<ACollector> gc) noexcept;
             /** during GC: forward immdiate children **/
-            static size_type forward_children(DVirtualSchematikaMachine & self, obj<ACollector> gc) noexcept;
+            static void forward_children(DVirtualSchematikaMachine & self, obj<ACollector> gc) noexcept;
             ///@}
         };
 
diff --git a/src/interpreter2/IGCObject_DClosure.cpp b/src/interpreter2/IGCObject_DClosure.cpp
index 99e834b8..ac9f1932 100644
--- a/src/interpreter2/IGCObject_DClosure.cpp
+++ b/src/interpreter2/IGCObject_DClosure.cpp
@@ -27,9 +27,9 @@ namespace xo {
             return self.shallow_move(gc);
         }
         auto
-        IGCObject_DClosure::forward_children(DClosure & self, obj<ACollector> gc) noexcept -> size_type
+        IGCObject_DClosure::forward_children(DClosure & self, obj<ACollector> gc) noexcept -> void
         {
-            return self.forward_children(gc);
+            self.forward_children(gc);
         }
 
     } /*namespace scm*/
diff --git a/src/interpreter2/IGCObject_DVsmApplyClosureFrame.cpp b/src/interpreter2/IGCObject_DVsmApplyClosureFrame.cpp
index a96ad2d7..2904c6be 100644
--- a/src/interpreter2/IGCObject_DVsmApplyClosureFrame.cpp
+++ b/src/interpreter2/IGCObject_DVsmApplyClosureFrame.cpp
@@ -27,9 +27,9 @@ namespace xo {
             return self.shallow_move(gc);
         }
         auto
-        IGCObject_DVsmApplyClosureFrame::forward_children(DVsmApplyClosureFrame & self, obj<ACollector> gc) noexcept -> size_type
+        IGCObject_DVsmApplyClosureFrame::forward_children(DVsmApplyClosureFrame & self, obj<ACollector> gc) noexcept -> void
         {
-            return self.forward_children(gc);
+            self.forward_children(gc);
         }
 
     } /*namespace scm*/
diff --git a/src/interpreter2/IGCObject_DVsmApplyFrame.cpp b/src/interpreter2/IGCObject_DVsmApplyFrame.cpp
index 9666fdec..c8701e58 100644
--- a/src/interpreter2/IGCObject_DVsmApplyFrame.cpp
+++ b/src/interpreter2/IGCObject_DVsmApplyFrame.cpp
@@ -27,9 +27,9 @@ namespace xo {
             return self.shallow_move(gc);
         }
         auto
-        IGCObject_DVsmApplyFrame::forward_children(DVsmApplyFrame & self, obj<ACollector> gc) noexcept -> size_type
+        IGCObject_DVsmApplyFrame::forward_children(DVsmApplyFrame & self, obj<ACollector> gc) noexcept -> void
         {
-            return self.forward_children(gc);
+            self.forward_children(gc);
         }
 
     } /*namespace scm*/
diff --git a/src/interpreter2/IGCObject_DVsmDefContFrame.cpp b/src/interpreter2/IGCObject_DVsmDefContFrame.cpp
index 2acd7b24..a574c84f 100644
--- a/src/interpreter2/IGCObject_DVsmDefContFrame.cpp
+++ b/src/interpreter2/IGCObject_DVsmDefContFrame.cpp
@@ -27,9 +27,9 @@ namespace xo {
             return self.shallow_move(gc);
         }
         auto
-        IGCObject_DVsmDefContFrame::forward_children(DVsmDefContFrame & self, obj<ACollector> gc) noexcept -> size_type
+        IGCObject_DVsmDefContFrame::forward_children(DVsmDefContFrame & self, obj<ACollector> gc) noexcept -> void
         {
-            return self.forward_children(gc);
+            self.forward_children(gc);
         }
 
     } /*namespace scm*/
diff --git a/src/interpreter2/IGCObject_DVsmEvalArgsFrame.cpp b/src/interpreter2/IGCObject_DVsmEvalArgsFrame.cpp
index d1d6a0b6..072f0e49 100644
--- a/src/interpreter2/IGCObject_DVsmEvalArgsFrame.cpp
+++ b/src/interpreter2/IGCObject_DVsmEvalArgsFrame.cpp
@@ -27,9 +27,9 @@ namespace xo {
             return self.shallow_move(gc);
         }
         auto
-        IGCObject_DVsmEvalArgsFrame::forward_children(DVsmEvalArgsFrame & self, obj<ACollector> gc) noexcept -> size_type
+        IGCObject_DVsmEvalArgsFrame::forward_children(DVsmEvalArgsFrame & self, obj<ACollector> gc) noexcept -> void
         {
-            return self.forward_children(gc);
+            self.forward_children(gc);
         }
 
     } /*namespace scm*/
diff --git a/src/interpreter2/IGCObject_DVsmIfElseContFrame.cpp b/src/interpreter2/IGCObject_DVsmIfElseContFrame.cpp
index 38f4881d..842199da 100644
--- a/src/interpreter2/IGCObject_DVsmIfElseContFrame.cpp
+++ b/src/interpreter2/IGCObject_DVsmIfElseContFrame.cpp
@@ -27,9 +27,9 @@ namespace xo {
             return self.shallow_move(gc);
         }
         auto
-        IGCObject_DVsmIfElseContFrame::forward_children(DVsmIfElseContFrame & self, obj<ACollector> gc) noexcept -> size_type
+        IGCObject_DVsmIfElseContFrame::forward_children(DVsmIfElseContFrame & self, obj<ACollector> gc) noexcept -> void
         {
-            return self.forward_children(gc);
+            self.forward_children(gc);
         }
 
     } /*namespace scm*/
diff --git a/src/interpreter2/IGCObject_DVsmSeqContFrame.cpp b/src/interpreter2/IGCObject_DVsmSeqContFrame.cpp
index 3d57aaa1..fb504b96 100644
--- a/src/interpreter2/IGCObject_DVsmSeqContFrame.cpp
+++ b/src/interpreter2/IGCObject_DVsmSeqContFrame.cpp
@@ -27,9 +27,9 @@ namespace xo {
             return self.shallow_move(gc);
         }
         auto
-        IGCObject_DVsmSeqContFrame::forward_children(DVsmSeqContFrame & self, obj<ACollector> gc) noexcept -> size_type
+        IGCObject_DVsmSeqContFrame::forward_children(DVsmSeqContFrame & self, obj<ACollector> gc) noexcept -> void
         {
-            return self.forward_children(gc);
+            self.forward_children(gc);
         }
 
     } /*namespace scm*/
diff --git a/src/interpreter2/facet/IGCObject_DLocalEnv.cpp b/src/interpreter2/facet/IGCObject_DLocalEnv.cpp
index ed9f18fd..dfa0cc30 100644
--- a/src/interpreter2/facet/IGCObject_DLocalEnv.cpp
+++ b/src/interpreter2/facet/IGCObject_DLocalEnv.cpp
@@ -27,9 +27,9 @@ namespace xo {
             return self.shallow_move(gc);
         }
         auto
-        IGCObject_DLocalEnv::forward_children(DLocalEnv & self, obj<ACollector> gc) noexcept -> size_type
+        IGCObject_DLocalEnv::forward_children(DLocalEnv & self, obj<ACollector> gc) noexcept -> void
         {
-            return self.forward_children(gc);
+            self.forward_children(gc);
         }
 
     } /*namespace scm*/
diff --git a/src/interpreter2/facet/IGCObject_DVirtualSchematikaMachine.cpp b/src/interpreter2/facet/IGCObject_DVirtualSchematikaMachine.cpp
index ddf77335..97168084 100644
--- a/src/interpreter2/facet/IGCObject_DVirtualSchematikaMachine.cpp
+++ b/src/interpreter2/facet/IGCObject_DVirtualSchematikaMachine.cpp
@@ -27,9 +27,9 @@ namespace xo {
             return self.shallow_move(gc);
         }
         auto
-        IGCObject_DVirtualSchematikaMachine::forward_children(DVirtualSchematikaMachine & self, obj<ACollector> gc) noexcept -> size_type
+        IGCObject_DVirtualSchematikaMachine::forward_children(DVirtualSchematikaMachine & self, obj<ACollector> gc) noexcept -> void
         {
-            return self.forward_children(gc);
+            self.forward_children(gc);
         }
 
     } /*namespace scm*/